Systems and methods of powering a refrigeration unit of a hybrid vehicle

ABSTRACT

Systems and methods for providing power to a refrigeration unit or an air conditioner used on a hybrid vehicle. The system includes an accumulation choke, a PWM rectifier, and a frequency inverter. The accumulation choke is configured to receive a first AC power, a second AC power, and a DC power. The accumulation choke and PWM rectifier convert the received power into an intermediate DC power having a peak voltage. The PWM rectifier provides the intermediate DC power to the frequency inverter. The frequency inverter converts the intermediate DC power to an output AC power. The frequency inverter provides the output AC power to the refrigeration unit.

RELATED APPLICATION

The present application claims the benefit of prior filed U.S.Provisional Patent Application No. 61/158,964 filed on Mar. 10, 2009,the entire content of which is hereby incorporated by reference.

BACKGROUND

Refrigeration units, e.g., for refrigerated trucks or rail cars,typically include an internal combustion engine which drives acompressor of the refrigeration unit via a belt. Some refrigerationunits also include means for plugging the unit into electrical mains(shore power) for powering the unit when the unit is not in transit. Theshore power powers an electric motor which drives the compressor via abelt.

SUMMARY

In one embodiment, the invention provides a power system for powering arefrigeration unit. The power system includes a first set ofconnections, a second set of connections, and a third set ofconnections. The first set of connections are configured to receivepower from a first power source, the first power source being a firsthigh-voltage AC power source. The second set of connections areconfigured to receive power from a second power source, the second powersource being a high-voltage DC power source. The third set ofconnections are configured to receive power from a third power source,the third power source being a second high-voltage AC power source. Thepower system couples the first power source to the refrigeration unitwhen power is received at the first set of connections, couples thesecond power source to the refrigeration unit when power is received atthe second set of connections but not the first set of connections, andcouples the third power source to the refrigeration unit when power isnot available from both the first and second set of connections.

In another embodiment, the invention provides a power system forpowering a refrigeration unit. The power system includes a firstconnection, a second connection, a third connection, and a powerconverter. The first connection is configured to receive power from afirst power source. Where the first power source is a first high-voltagealternating current (AC) power source. The second connection isconfigured to receive power from a second power source. Where the secondpower source is a high-voltage direct current (DC) power source. Thethird connection is configured to receive power from a third powersource. Where the third power source is a second high-voltage AC powersource. The power converter is configured to supply power to therefrigeration unit. The power system couples the first power source tothe power converter when power is received at the first connection,couples the second power source to the power converter when power isreceived at the second connection but not the first connection, andcouples the third power source to the power converter when power is notavailable from both the first and second connections.

In another embodiment, the invention provides a system for powering arefrigeration unit coupled with a hybrid vehicle having a plurality ofhigh-voltage batteries. The system includes a power system, arefrigeration control unit, and an engine. The power system is coupledto the plurality of high-voltage batteries and is configured to receivepower from a shore power source. The refrigeration control unit iscoupled to the power system, and receives an indication from the powersystem of the availability of power from the high-voltage batteries andthe shore power source. The engine is also coupled to the refrigerationcontrol unit. The refrigeration control unit links power from the powersystem to the refrigeration unit when power is available from the powersystem, and links the engine to the refrigeration unit when power is notavailable from the power system.

In another embodiment, the invention provides a method of powering arefrigeration unit. The method includes the acts of receiving at a firstinput a high-voltage DC power from a plurality of batteries of a hybridvehicle, receiving at a second input a high-voltage AC power from anelectric mains, connecting one of the first input and the second inputto a power converter based on a position of a switch, the connecting actcoupling one of the high-voltage DC power and the high-voltage AC powerto the power converter thereby resulting in a coupled power,disconnecting the coupled power from the power converter when theposition of the switch has changed, converting the coupled power into asecond high-voltage AC power, and providing the second high-voltage ACpower to the refrigeration unit.

The invention relates to systems and methods for powering arefrigeration or air conditioning unit used with a hybrid vehicle, suchas a truck or bus. In one embodiment, the invention uses high-voltagepower from the batteries of the hybrid vehicle to power therefrigeration unit, while maintaining the capability of using shorepower or operating the compressor using an internal combustion enginewhen the power available from the batteries is not available.

In another embodiment, the invention provides a system for providingpower to a refrigeration unit used on a hybrid vehicle. The systemincludes an accumulation choke, a PWM rectifier, and a frequencyinverter. The accumulation choke is configured to receive a first ACpower having a voltage range of about 150 to 600 VAC, a second AC powerof about 150 to 600 VAC, and a DC power having a voltage range of about263 to 408 VDC. The accumulation choke and PWM rectifier convert thereceived power into an intermediate DC power having a peak voltage ofabout 750 VDC. The PWM rectifier provides the intermediate DC power tothe frequency inverter. The frequency inverter converts the intermediateDC power to a variable output AC power having a voltage of about 0 to525 VAC and a frequency of about 0 to 100 Hertz (Hz). The frequencyinverter provides the output AC power to the refrigeration unit.

In another embodiment, the invention provides a system for providingpower to a refrigeration unit used on a hybrid vehicle. The systemincludes an accumulation choke, a PWM rectifier, and a frequencyinverter. The accumulation choke is configured to receive an AC powerhaving a voltage range of about 150 to 600 VAC and a DC power having avoltage range of about 263 to 408 VDC. The accumulation choke and PWMrectifier convert the received power into an intermediate DC powerhaving a peak voltage of about 750 VDC. The PWM rectifier provides theintermediate DC power to the frequency inverter. The frequency inverterconverts the intermediate DC power to an output AC power having avoltage of about 0 to 525 VAC. The frequency inverter provides theoutput AC power to the refrigeration unit. If the AC power and the DCpower are not available, the refrigeration unit is driven by an internalcombustion engine.

In yet another embodiment, the invention provides a method of providingpower to a refrigeration unit used on a hybrid vehicle. The methodincludes providing to a power unit a first AC power from an externalsource, providing to the power unit a DC power from high-voltagebatteries of the hybrid vehicle, determining if the first AC power issufficient to power the refrigeration unit, using the first AC power togenerate an output AC power if the first AC power is determined to besufficient to power the refrigeration unit, determining if the DC poweris sufficient to power the refrigeration unit, using the DC power togenerate the output AC power if the first AC power is not sufficient topower the refrigeration unit and the DC power is sufficient to power therefrigeration unit, generating the output AC power from a belt drivenalternator if the first AC power and the DC power are not sufficient topower the refrigeration unit, and providing the output AC power to therefrigeration unit.

In another embodiment, the invention provides a system for powering arefrigeration unit of a hybrid vehicle. The system includes an externalsource of power, a power unit for receiving AC power from the externalsource of power, a battery charger receiving AC power from the externalsource of power, and a plurality of batteries forming a high-voltagebattery for powering the hybrid vehicle. The power unit modifies the ACpower into an output AC power suitable to operate the refrigerationunit. The charger recharges the plurality of batteries.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram of a construction of a power system for ahybrid vehicle with a refrigeration unit.

FIG. 1B is a block diagram of an alternative construction of a powersystem for a hybrid vehicle with a refrigeration unit.

FIG. 2A is a schematic diagram of a construction of an accumulationchoke and a full-control PWM rectifier for use with three-phase ACpower.

FIG. 2B is a schematic diagram of a construction of an accumulationchoke and a half-control PWM rectifier for use with three-phase ACpower.

FIG. 3A is a schematic diagram of a construction of an accumulationchoke and a full-control PWM rectifier for use with DC power.

FIG. 3B is a schematic diagram of a construction of an accumulationchoke and a half-control PWM rectifier for use with DC power.

FIG. 4 is a block diagram of a construction of a system for powering arefrigeration unit of a hybrid vehicle.

FIG. 5 is a schematic diagram of a construction of a circuit of a powersystem for using AC or DC power to generate three-phase AC power.

FIG. 6 is a schematic diagram of a construction of a circuit forcontrolling the operation of the circuit of FIG. 5.

FIG. 7 is an alternative construction of a power system for poweringmultiple systems.

FIGS. 8A and 8B are a schematic diagram of another construction of apower system.

FIGS. 9A, 9B, 9C, and 9D are a schematic diagram of another constructionof a power system.

FIG. 10 is a block diagram of another construction of a system forpowering a refrigeration unit of a hybrid vehicle.

FIG. 11 is a schematic diagram of another construction of a circuit of apower system for using AC or DC power to generate three-phase AC power.

FIG. 12 is a schematic diagram of a construction of a full-control PWMrectifier, incorporating a pre-charge circuit, for use with three-phaseAC power.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof encompass direct and indirect mountings, connections, supports,and couplings. Further, “connected” and “coupled” are not restricted tophysical or mechanical connections or couplings.

FIG. 1A shows a block diagram of a construction of a system 100 forpowering a refrigeration unit 105 using power from a belt drivenalternator 110, from high-voltage batteries 115 of a hybrid vehicle, andfrom shore power 120. A switch 125 selects which of the three powersources 110, 115, and 120 is used. In some constructions, the switch 125is a manual switch, where a user selects which power source 110, 115,and 120 to use. In other constructions, the switch 125 is automatic,where a controller senses which power source(s) are providing sufficientpower to operate the refrigeration unit 105 and selects the mostappropriate power source to use. For example, in some embodiments, shorepower 120 is used whenever it is available, followed by power from thehigh-voltage batteries 115, and finally by power from the belt drivenalternator 110. In addition, the controller may control operation of aninternal combustion engine used to drive the alternator, turning on theengine when there is insufficient power available from the shore power120 or the high-voltage batteries 115, and turning off the engine whenthere is sufficient power available from either the shore power 120 orthe high-voltage batteries 115, thus saving energy (i.e., fuel).

In some constructions, the power available from the belt drivenalternator 110 is about 150 to 600 volts AC (VAC), the power availablefrom the high-voltage batteries 115 is about 263 to 408 volts DC (VDC),and the power available from shore power 120 is about 150 to 600 VAC. Inthe construction shown, AC power is assumed to be three-phase, howeverthe invention contemplates the use of single-phase AC power as well.

Depending on the position of the switch 125, set either manually orautomatically, the power from one of the power sources 110, 115, and 120is applied a power converter 130 including an accumulation choke 135, apulse-width-modulated (PWM) rectifier 140, and a frequency inverter 145.The accumulation choke 135 is coupled to the PWM rectifier 140. Theaccumulation choke 135 operates with the PWM rectifier 140 toconvert/modify the power received from the belt driven alternator 110,the high-voltage batteries 115, or the share power 120 to a DC voltagehaving a maximum amplitude of about 750 VDC. The DC voltage is providedto the frequency inverter 145 which converts the DC voltage to avariable voltage of 0 to 525 VAC having a frequency of about 0 to 100Hz, which is provided to the refrigeration unit 105. In someconstructions, the DC power from the PWM rectifier 140 is also used tosupply a DC chopper for an electric heater. The DC chopper provides DCpower having a variable voltage of about 0 to 750 V DC.

FIG. 1B shows a block diagram of an alternate construction of a system100′ for powering a refrigeration unit 105 using power from a beltdriven alternator 110, from high-voltage batteries 115 of a hybridvehicle, and from shore power 120. Again a switch 125′ selects which ofthe three power sources 110, 115, and 120 is used. However, in theconstruction shown, the switch 125′ has multiple throws such that whenpower from the belt driven alternator 110 is selected, the alternator110 is connected directly to the PWM rectifier 140, bypassing theaccumulation choke 135. Except for the alternator 110 being connecteddirectly to the PWM rectifier 140, the operation of the system 100′ isthe same as the operation of system 100 described above. Theconstruction shown in FIG. 1B can be used when the inductance of thebelt driven alternator 110 is great enough that the accumulation choke135 is not necessary.

FIG. 2A shows a schematic diagram of a construction of the accumulationchoke 135 and a full-controlled PWM rectifier 140′. The accumulationchoke 135 includes a plurality of inductors 150. The full-controlled PWMrectifier 140′ includes six insulated gate bipolar transistors (IGBT)155-160, each IGBT 155-160 having a diode 165-170 connected across itscollector and emitter, and a capacitor 175.

FIG. 2B shows a schematic diagram of a construction of the accumulationchoke 135 and a half-controlled PWM rectifier 140″. The accumulationchoke 135 includes a plurality of inductors 150. The half-controlled PWMrectifier 140″ includes three insulated gate bipolar transistors (IGBT)158-160, each IGBT 158-160 having a diode 168-170 connected across itscollector and emitter, three diodes 155-157 connected in an upper branchof the half-controller PWM rectifier 140″, and a capacitor 175.

FIG. 3A shows a schematic representation of the accumulation choke 135and a full-controlled PWM rectifier 140′ for use with DC input powerfrom the high-voltage batteries 115. The accumulation choke 135 and thefull-controlled PWM rectifier 140′ include all the same components asdescribed above with respect to FIG. 2A; however, the DC input voltageis applied to each inductor 150 and the upper IGBTs 155-157 are not used(i.e., they remain open).

FIG. 3B shows a schematic diagram of a construction of the accumulationchoke 135 and a half-controlled PWM rectifier 140″ for use with DC inputpower from the high-voltage batteries 115. The accumulation choke 135includes a plurality of inductors 150. The half-controlled PWM rectifier140″ includes three insulated gate bipolar transistors (IGBT) 158-160,each IGBT 158-160 having a diode 168-170 connected across its collectorand emitter, three diodes 155-157 connected in an upper branch of thehalf-controller PWM rectifier 140″, and a capacitor 175.

FIG. 4 shows a block diagram of a construction of a hybrid vehiclesystem 200 including a refrigeration unit 205. The system 200 includes,among other things, a 12 VDC battery 210, a set of high-voltagebatteries 215, a vehicle controller 220, a refrigeration unit controller225, a refrigeration power system 230 including a connection to shorepower 240, a refrigeration unit power switch 245, and a generator setincluding an internal combustion engine 250 driving an alternator 255.In some constructions, an internal combustion engine 250 drives acompressor and fans of the refrigeration unit 205 directly by one ormore belts. In some constructions, an electric motor is powered by theshore power 240 and drives a compressor and fans of the refrigerationunit 205 directly by one or more belts.

A master switch 260 enables the entire system 200. The power system 230receives power from the shore power connection 240 and the high-voltagebatteries 215, and provides power, if available, from either the shorepower connection 240 or the high-voltage batteries 215 to therefrigeration unit power switch 245.

The vehicle controller 220 provides an indication to the power system230, via line 265, that power is available from the high-voltagebatteries 215. The power system 230 provides to the refrigeration unitcontroller 225, via line 270, an indication that power is available fromeither the shore power connection 240 or the high-voltage batteries 215,and is being provided to the refrigeration unit power switch 245. Therefrigeration unit controller 225 provides to the power unit 230, vialine 275, an indication that the refrigeration unit 205 is on or off.The refrigeration unit controller 225 controls the refrigeration unitpower switch 245, switching between power provided by the power system230 or, if power is not available from the power system 230, powerprovided by the belt driven alternator 255. If the refrigeration unit205 is on, power is provided to the refrigeration unit 205 by the powersystem 230 if power is available from either the shore power connection240 or the high-voltage batteries 215. If power is not available fromthe power system 230 and the refrigeration unit 205 is on, therefrigeration unit controller 225 turns on the internal combustionengine 250 which drives, via a belt, the alternator 255. The alternator255 then provides power to the refrigeration unit power switch 245,which is set, by the refrigeration unit controller 225, to provide thepower from the alternator 255 to the refrigeration unit 205. Inalternative constructions, there may be no alternator present in thesystem 200, instead the internal combustion engine 250 drives acompressor and fans of the refrigeration unit 205 directly.

FIG. 5 shows a construction of a portion of the power system 230. Thesystem 230 includes an AC power connector 300 and a DC power connector305. The AC connector 300 includes three connections L1, L2, and L3 forconnecting three-phase shore power (if available) to the system 230. TheDC connector 305 includes a positive 310 and a negative 315 connectionfor connecting to the high-voltage batteries 115. Each input line L1,L2, L3, 310, and 315 is connected to the rest of the system 230 througha fuse FSUP1-FSUP5 sized appropriately for the voltage and currentreceived on its respective input line L1, L2, L3, 310, and 315. Eachinput line L1, L2, L3, 310, and 315 is also connected to the powerconverter 130 through a normally-open relay 320-326. As discussed below,when shore power is available, the normally-open relays 320-322 areclosed to provide the AC shore power to the power converter 130, andwhen shore power is not available and DC power from the high-voltagebatteries 115 is available, the normally-open relays 323-326 are closedto provide the DC power to the power converter 130. When the ACnormally-open relays 320-322 are closed, the DC normally-open relays323-326 are open, and when the DC normally-open relays 323-326 areclosed, the AC normally-open relays 320-322 are open. In someconstructions, an interlock module monitors relays 320-322 and 323-326to ensure that only one of the relay groups 320-322 or 323-326 is closedat any time.

The system 230 also includes AC pre-charging circuits havingnormally-open relays 330 and 331 and resistors 332 and 333, and a DCpre-charging circuit including a normally-open relay 334 and resistor335. The pre-charging circuits are used when power is initially appliedto the power system 230, and during a transition from AC power to DCpower or from DC power to AC power. During a transition, thepre-charging circuits maintain power to the power converter 130, andallow the AC or DC power to be completely removed before the DC or ACpower, being transitioned to, is connected.

As discussed above with respect to FIGS. 1-3, if available, AC or DCpower is provided to the accumulation choke 135 and the PWM rectifier140 of the power converter 130. The accumulation choke 135 and the PWMrectifier 140 convert the AC or DC power to DC power having a maximumvoltage of about 750 volts. The DC power is the provided to the inverter145 which converts the DC power to three-phase AC power having avariable voltage of 0 to 525 volts and frequency of about 0 to 100 Hz.In the construction shown in FIG. 4, this AC power is then provided tothe refrigeration unit 205 via the refrigeration unit power switch 245.In some constructions, the DC power from the PWM rectifier 140 is alsoused to supply a DC chopper for an electric heater. The DC chopperprovides DC power having a variable voltage of about 0 to 750 V DC.

FIG. 6 shows a circuit 350 for controlling the application of AC or DCpower to the power converter 130 for the system 230 shown in FIG. 5. Thecircuit 350 includes an AC delay 355 having a normally-closed switch 360and a normally-open switch 365, a DC delay 370 having a normally-closedswitch 375 and a normally-open switch 380, and a plurality of coils390-396 for closing corresponding normally-open relays 320-326 shown inFIG. 5. A switch 400 selects either AC or DC power. In the constructionshown, the switch 400 is a manual switch requiring an operator to selectthe AC or DC power. In some embodiments, the switch 400 is an automaticswitch where AC power is automatically chosen if available, and if ACpower is not available but DC power is available, DC power isautomatically chosen. In other embodiments, DC power is automaticallychosen if available and AC power is chosen if available when DC power isnot available. In some embodiments, if the switch 400 is off, andneither AC nor DC power is available, an internal combustion enginedrives the refrigeration unit directly when the refrigeration unit ison.

When the switch 400 is put into the AC position, power is provided tothe AC delay 355 and to the AC pre-charge coil 395. The power providedto the AC pre-charge coil 395 closes the AC pre-charge normally-openrelays 330-331 (FIG. 5) applying AC power through resistors 332 and 333to the power converter 130. After a delay period (e.g., five seconds),the AC delay 355 opens the AC normally-closed switch 360 and closes theAC normally-open switch 365. When the AC normally-closed switch 360opens, power is removed from the AC pre-charge coil 395 and the ACpre-charge normally-open relays 330-331 open. When the AC normally-openswitch 365 closes, power is applied to the AC coil 396 and the ACnormally-open relays 320-322 close providing three-phase AC power to thepower converter 130.

When the switch 400 is put into the DC position, power is provided tothe DC delay 370 and to the DC pre-charge coil 391, and to DC negativecoil 390. The power provided to the DC pre-charge coil 391 closes the DCpre-charge normally-open relay 334 (FIG. 5) applying DC power throughresistor 335 to the power converter 130. The power provided to the DCnegative coil 390 closes the normally-open relay 326 connecting thenegative connection 315 from the high-voltage batteries 215 to the powerconverter 130. After a delay period (e.g., five seconds), the DC delay370 opens the DC normally-closed switch 375 and closes the DCnormally-open switch 380. When the DC normally-closed switch 375 opens,power is removed from the DC pre-charge coil 391 and the DC pre-chargenormally-open relay 324 opens. When the DC normally-open switch 380closes, power is applied to the DC coils 392-394 and the DCnormally-open relays 323-325 close providing DC power to the powerconverter 130.

FIG. 7 shows an alternative construction of a power converter 405 wheremultiple power converters 410-425 are employed for powering variousdevices such as a compressor motor 430, an electric heater 435, anevaporator fan 440, and a condenser fan 445.

FIGS. 8A and 8B show a schematic diagram of a construction of the powersystem 230 (FIG. 4). When system power is turned on (switch 260 in FIG.4 is closed), normally-open relay K7 closes. If shore power isavailable, i.e., three-phase AC power is provided to L1, L2, L3, and aphase select module 450 receives power from normally-open relay K7 andthe AC power lines L1, L2, L3. The phase select module 450 then providespower to line 8EA. The power on line 8EA initiates a five second delaytimer 455 and simultaneously powers coil P. The power to coil P closesnormally-open relays P1 and P2, and opens normally-closed relay P2.After five seconds, the five second delay timer 455 provides power tooutput MPT which is provided to the refrigeration unit controller 225 toindicate that power is available from the power system 230 (FIG. 4). Ifthe refrigeration unit controller 225 indicates that the refrigerationunit 205 is on, normally-open relay K13 is closed providing power tocoil MCA. The power to coil MCA causes normally-open relays MCA toclose, supplying the AC shore power to the power converter 130, which inturn supplies power to a condenser motor 460 (providing normally-openrelays K14 are closed).

If AC shore power is not available, normally-closed relay P2 is closed.If the vehicle controller 220 (FIG. 4) indicates that vehicle power isavailable, the vehicle controller 220 provides power to a five seconddelay timer 465. After a five second delay, the timer 465 allows powerto be applied to a coil T closing normally-open relay T1 and providingpower to output MPT, which is provided to the refrigeration unitcontroller 225 to indicate that power is available from the power system230 (FIG. 4). If the refrigeration unit controller 225 indicates thatthe refrigeration unit 205 is on, normally-open relay K13 is closed,providing power to coil MCB. The power to coil MCB causes normally-openrelays MCB to close, supplying the DC power from the high-voltagebatteries 215 to the power converter 130, which in turn supplies powerto the condenser motor 460 (providing normally-open relays K14 areclosed).

If neither AC shore power nor DC power from the high-voltage batteries215 is available, the output MPT to the refrigeration unit controller225 is low and the refrigeration unit controller 225 starts the engine250 which drives the refrigeration unit 205 directly.

FIGS. 9A, 9B, 9C, and 9D show a schematic diagram of an alternativeconstruction of a power system 500.

FIG. 10 shows an alternate construction of a power system 505. Thesystem 505 includes a first AC power connector 510, a second AC powerconnector 515, and a DC power connector 520. The first AC connector 510includes three connections L1, L2, and L3 for connecting three-phasepower from the belt driven alternator 255 to the system 505. The secondAC connector 515 includes three connections L1′, L2′, and L3′ forconnecting three-phase shore power (if available) to the system 505. TheDC connector 520 includes a positive connection 525 and a negative 530connection for connecting to the high-voltage batteries 215 to thesystem 505. Each input line L1, L2, L3, L1′, L2′, L3′, 525, and 530 isconnected to the rest of the system 505 through a fuse FSUP1-FSUP8 sizedappropriately for the voltage and current received on its respectiveinput line L1, L2, L3, L1′, L2′, L3′, 525, and 530. Each input line L1,L2, L3, L1′, L2′, L3′, 525, and 530 is also connected to the powerconverter 130 through a normally-open relay 535-544. As discussed below,when shore power is available, the normally-open relays 538-540 areclosed to provide the AC shore power to the power converter 130, andwhen shore power is not available and DC power from the high-voltagebatteries 215 is available, the normally-open relays 541-544 are closedto provide the DC power to the power converter 130. When neither shorepower nor DC power is available, the normally-open relays 535-537 areclosed to provide AC power from the alternator 255 to the powerconverter 130. Only one set of normally-open relays 535-537, 538-540, or541-544 are closed at any time.

The system 505 also includes first AC pre-charging circuits havingnormally-open relays 550 and 551 and resistors 552 and 553, second ACpre-charging circuits having normally-open relays 555 and 556 andresistors 557 and 558, and a DC pre-charging circuit having anormally-open relay 560 and a resistor 561. The pre-charging circuitsare used when power is initially applied to the power system 505, andduring a transition between one input power to another to maintain powerto the power converter 130 during the transition, and allowing the powerbeing transitioned from to be completely removed before the power beingtransitioned to is connected.

As discussed above with respect to FIGS. 1-3, if available, AC or DCpower is provided to the accumulation choke 135 and the PWM rectifier140 of the power converter 130 convert the AC or DC power to DC powerhaving a maximum voltage of about 750 volts. The DC power is theprovided to the inverter 145, which converts the DC power to three-phaseAC power having a voltage of 0 to 525 volts. In the construction shownin FIG. 4, this AC power is then provided to the refrigeration unit 205via the refrigeration unit power switch 245.

FIG. 11 shows a circuit 600 for controlling the application of the firstAC power, the second AC power, or the DC power to the power converter130 for the system 505 shown in FIG. 10. The circuit 600 includes afirst AC delay 605 having a normally-closed switch 610 and anormally-open switch 615, a second AC delay 620 having a normally-closedswitch 625 and a normally-open switch 630, a DC delay 635 having anormally-closed switch 640 and a normally-open switch 645, and aplurality of coils 650-658 for closing corresponding normally-openrelays 534-544, 550-551, 555, 556, and 560 shown in FIG. 10. A switch660 selects either the first AC power, the second AC power, or the DCpower. In the construction shown, the switch 660 is a manual switchrequiring an operator to select the power. In some constructions, theswitch 660 is an automatic switch where the second AC power (shorepower) is automatically chosen if available, and if the first AC poweris not available but DC power is available, the DC power isautomatically chosen. If neither the second AC power nor the DC power isavailable, the switch automatically chooses the first AC power. Thecircuit 600 operates similar to the operation of circuit 350 of FIG. 6with the addition of a second AC power.

In some constructions, a liquid cooling system of the hybrid vehicle isused to cool one or more components of the power system 230 (e.g., thepower converter 130) and/or one or more components of the alternator 255(e.g., the belt driven alternator 110). In other constructions, a liquidcooling system of the refrigeration unit 205 is used to cool one or morecomponents of the power system 230 and/or one or more components of thealternator 255.

In some constructions, shore power is provided to a charging circuit, inaddition to the power system 230, for charging the high-voltagebatteries 215. In some constructions, the refrigeration unit 205 isoperated exclusively using either DC power from the high-voltagebatteries 215 or AC shore power 240.

FIG. 12 shows a schematic diagram of an alternative construction of afull-controlled PWM rectifier 700 incorporating a pre-charging circuit705. The full-controlled PWM rectifier 700 includes six insulated gatebipolar transistors (IGBT) 155-160, each IGBT 155-160 having a diode165-170 connected across its collector and emitter, and operates thesame as system 100 described above. The pre-charging circuit 705includes a capacitor 715, a resistor 720, a diode 725, and an IGBT 730.The pre-charging circuit 705 operates to buffer a current surgeencountered when switching from one power source to a second powersource, and eliminates the need for the pre-charging and delay circuitsdescribed for the controllers above. The pre-charging circuit 705operates by opening the IGBT 730 prior to transitioning the powersource. Applying the second power source and removing the first powersource while the IGBT 730 is open. The IGBT 730 is held open until thecapacitor 715 is fully charged forcing current to travel through theresistor 720. Once the capacitor 715 is fully charged, the IGBT 730 isclosed.

Constructions of the invention are capable of being used in non-hybridvehicles, receiving AC power from an alternator of the vehicle duringoperation of the vehicle and having a shore power connection for usewhen the vehicle is not operating.

Thus, the invention provides, among other things, systems and method forpowering a refrigeration unit of a hybrid vehicle.

What is claimed is:
 1. A power system for powering a refrigeration unit,the power system comprising: a first connection configured to receivepower from a first power source, the first power source being a firsthigh-voltage alternating current (AC) power source; a second connectionconfigured to receive power from a second power source, the second powersource being a high-voltage direct current (DC) power source; a thirdconnection configured to receive power from a third power source, thethird power source being a second high-voltage AC power source; a powerconverter configured to supply power to the refrigeration unit, whereinthe power converter includes an accumulation choke and a PWM rectifierconfigured to receive the first high-voltage AC power, the secondhigh-voltage AC power, and the high-voltage DC power and convert thereceived power to a second DC power; and a switch connecting one of thefirst connection, the second connection and the third connection to thepower converter; wherein the power system couples the first power sourceto the power converter based on a position of the switch when power isreceived at the first connection, couples the second power source to thepower converter based on a position of the switch when power is receivedat the second connection but not the first connection, and couples thethird power source to the power converter based on a position of theswitch, and wherein the PWM rectifier includes: a plurality of diodesconfigured as a bridge rectifier, a plurality of electronic switches,one of the plurality of electronic switches coupled across each of theplurality of diodes, and a pre-charging circuit maintaining power to thepower converter when switching between the first power source, thesecond power source, and the third power source.
 2. The system of claim1, wherein the second DC power is between about 0 and 750 volts.
 3. Thesystem of claim 1, wherein the first high-voltage AC power sourceincludes a shore power.
 4. The system of claim 1, wherein thehigh-voltage DC power source includes a plurality of high-voltagebatteries used to power a hybrid vehicle.
 5. The system of claim 1,wherein the second high-voltage AC power source includes a belt-drivenalternator.
 6. The system of claim 1, wherein the first high-voltage ACpower source includes a shore power, the high-voltage DC power sourceincludes a plurality of high-voltage batteries used to power a hybridvehicle, and the second high-voltage AC power source includes abelt-driven alternator.
 7. A system for powering a refrigeration unitcoupled with a vehicle having a plurality of high-voltage batteries, thesystem comprising: a power system coupled to the plurality ofhigh-voltage batteries, the power system configured to receive powerfrom a shore power source, and the power system configured to receivepower from an alternator, wherein the power system includes a powerconverter having an accumulation choke and a PWM rectifier, the powerconverter configured to receive one of a high-voltage DC power from theplurality of high-voltage batteries, a high-voltage AC power from theshore power source, and a high-voltage AC power from the alternator andto convert the received power into a second high-voltage DC power, thepower system also including a switch connecting one of the shore powersource, the alternator and the plurality of high-voltage batteries tothe power converter based on a position of the switch; a refrigerationcontrol unit coupled to the power system, the refrigeration control unitreceiving an indication from the power system of the availability ofpower from the high-voltage batteries, the shore power source, and thealternator; and wherein the refrigeration control unit links power fromthe power system to the refrigeration unit when power is available fromthe power system, wherein the PWM rectifier includes: a plurality ofdiodes configured as a bridge rectifier, a plurality of electronicswitches, one of the plurality of electronic switches coupled acrosseach of the plurality of diodes, and a pre-charging circuit maintainingpower to the power converter when switching between the shore powersource, the alternator, and the plurality of high-voltage batteries. 8.The system of claim 7, wherein the power system includes a frequencyinverter configured to receive the second high-voltage DC power from thePWM rectifier and convert the second high-voltage DC power to an ACvoltage and to provide the AC voltage to the refrigeration unit.
 9. Amethod of powering a refrigeration unit, the method comprising:receiving at a first input a high-voltage DC power from a plurality ofbatteries of a hybrid vehicle; receiving at a second input ahigh-voltage AC power from an electric mains; receiving at a third inputa third high-voltage AC power from an alternator; connecting one of thefirst input, the second input and the third input to a power converterbased on a position of a switch, the connecting act coupling one of thehigh-voltage DC power, the high-voltage AC power, and the thirdhigh-voltage AC power to the power converter thereby resulting in acoupled power; disconnecting the coupled power from the power converterwhen the position of the switch has changed; converting the high-voltageDC power into a second high-voltage AC power by directing thehigh-voltage DC power through an accumulator choke and a PWM rectifierwhen the high-voltage DC power is coupled to the power converter andconverting the high-voltage AC power into the second high-voltage ACpower by directing the high-voltage AC power through the accumulatorchoke and the PWM rectifier when the high-voltage AC power is coupled tothe power converter; providing the second high-voltage AC power to therefrigeration unit; and directing one of the high-voltage DC power andthe high-voltage AC power through a pre-charging circuit at an output ofthe PWM rectifier, the pre-charging circuit maintaining power to thepower converter when switching between the first input, the secondinput, and the third input.
 10. The system of claim 7, wherein thepre-charging circuit buffers a current surge when an input power isswitched from a first power source to a second power source.
 11. Thesystem of claim 1, wherein the PWM rectifier is configured to receivethe second high-voltage AC power directly such that the secondhigh-voltage AC power bypasses the accumulation choke.
 12. The system ofclaim 7, wherein the power system is coupled to an alternator, and thePWM rectifier is configured to: receive one of the high-voltage DC powerfrom the plurality of high-voltage batteries, the high-voltage AC powerfrom the shore power source, and a third high-voltage AC power from thealternator, and to convert the received power into the secondhigh-voltage DC power.
 13. The system of claim 12, wherein the PWMrectifier is configured to receive the third high-voltage AC powerdirectly such that the third high-voltage AC power bypasses theaccumulation choke.
 14. The method of claim 9, further comprising:receiving at a third input a third high-voltage AC power from analternator; connecting one of the first input, the second input and thethird input to a power converter based on the position of the switch,the connecting act coupling one of the high-voltage DC power, thehigh-voltage AC power, and the third high-voltage AC power to the powerconverter thereby resulting in a coupled power; converting the thirdhigh-voltage AC power into the second high-voltage AC power by directingthe third high-voltage AC power through the PWM rectifier when the thirdhigh-voltage AC power is coupled to the power converter.
 15. The systemof claim 1, wherein the switch is an automatic switch, wherein acontroller automatically selects a position of the automatic switch toconnect one of the first connection, the second connection and the thirdconnection to the power converter.
 16. The system of claim 7, whereinthe switch is an automatic switch, wherein a controller automaticallyselects a position of the automatic switch to connect one of the shorepower source, the alternator and the high-voltage batteries to the powerconverter.
 17. The method of claim 9, wherein the switch is an automaticswitch, wherein a controller automatically selects a position of theautomatic switch to connect one of the first input, the second input andthe third input to the power converter.
 18. The system of claim 1,wherein the switch is a manual switch, wherein a user selects a positionof the manual switch to connect one of the first connection, the secondconnection and the third connection to the power converter.
 19. Thesystem of claim 7, wherein the switch is a manual switch, wherein a userselects a position of the manual switch to connect one of the shorepower source, the alternator and the high-voltage batteries to the powerconverter.
 20. The method of claim 9, wherein the switch is a manualswitch, wherein a user selects a position of the manual switch toconnect one of the first input, the second input and the third input tothe power converter.